v0.18.0 — pump status/alarm/runtime entities + read-only pump schedule

[0.18.0] - 2026-07-02

The Tuya sand-filter pump is now a first-class device.

Added

• Pump entities (live-verified against the SX2100 via the cloud shadow
  API): status (DP125), alarm code (DP127), error code (DP114), time
  remaining (DP110), mesh/link diagnostic (DP119), and the thing-model's
  second toggle DP106 ("Filter switch", disabled by default — its standalone
  effect is unverified).
• Pump schedule (read-only): the pump's internal timer program
  (skdl_filter, same 7-slot blob as the chlorinator's) is polled from the
  cloud and exposed as a "Schedules" sensor with full slot details, and
  included in the intex_pool.get_schedule service response (pump key).
  Write support can follow once slot semantics are verified on the hardware.